• You do not have to drive to the mall, park, hike inland for a mile or so, buy stuff, hike back, and drive home.

• You can shop whenever you want. These stores are always open. If you get an urge to book a trip at 2 A.M., you can work out all the details, and have tickets coming your way even though all real travel agents are asleep.

• The minute you enter an online store, you can find what you want a lot faster than you can going from department to department in a big mall store.

• Purchases that involve purely electronic transactions can be completed in a few seconds (or minutes, on a very busy day). For instance, several online stock-brokers promise that trades will be completed within ten seconds. If you reserve a car, flight, or hotel via the Web, you get confirmation in less than a minute.

You’ll save even more time if you use our book. We steer you past the biggest time-wasters for Web shoppers, such as:

• Web sites that pretend to be stores but are just brochures advertising a retail store or mail-order company. These sites may offer online catalogs, but they force you to call their offices to buy anything, or, worse, urge you to come on down to the mall outside a city 2,000 miles from your home.

• Web sites that look like stores but are actually just the owner’s opinions. For instance, if you go to a site that sounds as if it might sell CDs, you may discover what someone thinks of a new band, period.

• Web sites that are lists of other Web sites. Most of these lists include every site that has anything to do with the topic, including university courses, personal pages, magazines, newsgroups, and, oh, some stores. Depending on the dedication of the list maker, these links may be 5% to 20% broken. The best-maintained lists include a wide range of sites, from information hoards to online stores, without extensive evaluation of the real worth of the sites, and with descriptions that are often a bit vague, leaving one unsure whether or not a particular site actually sells stuff.

• Graphics-heavy sites that take forever to download.

• Amateur and back-alley sites that try to sell you their products without using a secure connection.

Starting your computer, getting connected to the Web, and deciding where to go to shop: these take more time than they should, particularly if you are using an older computer and regular phone lines. Other ways you might spend more time than you expected:

• You may get distracted by all the neat products. If you are browsing rather than looking for one particular item, you can enjoy yourself for quite a while, learning about a product category, considering various products, comparing prices. Oddly, most people do not notice time passing when they are doing this kind of research, so you may easily pass half an hour or more at a giant store, amusing yourself, downloading free software, playing this or that tune. Strictly speaking, this takes time. But because it’s fun (and informative), most people don’t object.

• Filling in a store’s registration or order form for the first time may involve typing your name and address into little slots, which can take a few minutes if you are a hunt-and-peck keyboarder.

• When you buy a physical item such as a book, CD, or computer, you do have to wait a day or two for delivery, or a week if you decide to save money on shipping. But for many people, getting a book or CD within a day or two is good enough, and not having to take an hour or so to go to a physical store is the real time-saver.

Yes, even though you pay for shipping, you can generally save a lot online, compared to what you might have to spend in a retail store built out of steel, glass, and concrete blocks.

Every online store can offer better prices than their physical cousins, because each online sale carries less overhead. Even if the company has retail outlets, an online sale does not carry the burden of expenses that must be charged to retail sales.

An online store has:

• No rent, air-conditioning, heating, or janitorial services for a retail showroom

• No salesclerks out on the floor

• No paper catalog, no postage

In fact, some online stores have no warehouses, either. Of course, like a retail operation, an online store has to pay someone to maintain a database with their current inventory.

And unlike their physical counterparts, the online store has to hire programmers to enable credit card verification and purchases over the Web, Web designers to make the site easy to visit, and content experts to post descriptions of all the products. Those hires cost major bucks, but if the store reaches a certain volume, a small profit margin can cover all those Web-related expenses.

A few stores don’t even make a profit on each sale. They offer huge discounts, basically selling at whatever they paid for a product, hoping to make money on banner ads or links to partner sites. Are these store owners crazy? In Silicon Valley, they’re considered brilliant pioneers.

For some kinds of products, such as CDs and books, you’ll find a few stores competing primarily on price, so discounts drop even more, and in the shops that get the biggest discounts (because they buy the most), you may even end up paying less than small retail shop owners usually pay their wholesalers.

In fact, if your experience is like ours, you will be amazed how many strange and wonderful products other people have been buying for years. Suddenly you see how incredibly specialized some products have become, and how many twists and turns there are in customization and service, because the Web merchants are trying to outdo each other.

The amount of information you get on each product varies enormously from site to site, but if you go to stores we recommend for their product descriptions, you will learn a lot, probably more than you could pick up walking around and talking with salespeople in a regular store.

Instead of dealing with a clerk who hardly knows what products lie under the glass countertop, you get a product description that often includes a list of specific features and benefits, system requirements, optional add-on products, and possibly reviews by critics and other customers. Not every online store piles on the info like this, but the best ones do.

And the rest of the Web acts as a giant clearinghouse for reviews, surveys, gossip, and research, so if you are new to a product arena, you can learn from the stores and these other Web sites what kind of products are available, what differentiates the good from the mediocre, and what features you might really want. Online shoppers, in general, are better informed than their mail-order cousins or mall denizens.

After you buy a product, you may be able to get a little (only a little) phone support from the store, mostly about assembling or installing. But for real technical support you have to call the manufacturer.

Some people tell us that anonymity is a major attraction of shopping online.

You don’t have to push past slowpokes in the crowded aisles; you don’t have to wait for a salesclerk to finish slurping a soda; you don’t have to suffer embarrassment as you buy intimate apparel or health products.

On the other hand, people build these sites, and you can definitely tell which site-builders are friendly and which ones just don’t care what you think.

Even though you are looking at the store through the screen of a computer, you get a feeling for these people behind the site. And naturally, you’re going to gravitate toward the sites that seem to understand what you want to do, how you feel, and what questions you might ask.

You don’t have to wait while they change the cash register tape, or finish planning dinner on the phone; but you still get a sense of their attitudes, which range from "We always put our own convenience first," to "We have worked like heck to make this site easy for you."

Yes, but the amount and quality vary from one product category to another.

If you are shopping for a CD, for instance, you can often download parts of songs and listen to them for free. (Even after you leave the site, you can listen to the snippets or tracks again, because they are sitting on your hard disk.) Ditto for clips of video.

Also free, or almost so, are tons of information you used to have to pay for. For instance, in the past if you wanted to get a stock quote, you phoned your broker, who charged you an annual fee for your account, plus a commission on each trade. Now you can get 20-minutes-old quotes free from any online broker, and many also offer real-time quotes for free. Similarly, the information that brokerages developed (and charged high rates for) is now available in part for free, and in part for a few bucks per report. In the past you could also get rates and fares directly from individual airlines, hotel chains, and car rental companies, but you had to go to a travel agent to get detailed comparisons of the offerings of all the companies. Now you get those comparisons for free online, and the online agencies will make your reservations pronto, also for free, or for a small "membership" fee.

Sure. In fact, more people use the Web for research than for purchases.

There are some real benefits to buying locally. You have a person you can talk to if you have a complaint; you can touch and feel and smell the merchandise; you can have a café latte while you are resting after carrying your purchases down the escalator.

One downside to learning about products on the Web, then going to your local retailer or mall, is that, even though you have discovered the perfect product online, your local store may not carry that particular item, manufacturer, or type of product. The store may have something that is a little better and a little more expensive, and several that are cheaper or worse.

Instead of using the Web to locate the "perfect" product, use the online information to develop a set of criteria that really matter to you. "My new cell phone must be 900 MHz, but I don’t care about any calling area outside of my city, and I do not need voice mail, just a phone number to call back, and . . ." That way you can see if your local store’s product (whatever the vendor, whatever other features it has) actually meets your criteria.

Your credit card information is safer online, within a secure shopping area, than it is when you give your card to a waiter at a restaurant or a clerk at a gas station. Far more credit card fraud stems from stolen paper receipts than from hackers intercepting transmissions to and from a secure shopping site.

But the real question is: What will the store do with your email address and street address? Will the store sell that to other companies, so you end up getting junk email and paper catalogs?

Recently, the Federal Trade Commission athttp://www.ftc.gov/ found that 86% of online stores provided no information about how they would use this kind of demographic data. Reasonably enough, many customers at these stores have refused to provide such information at one time or another, and 40% have occasionally provided fake information, which often results in the credit card companies rejecting the request to charge a purchase. Eighty percent of Web users said they wouldn’t object if the stores would just issue a statement promising not to resell the personal data.

Many of the stores we like do provide what they call a Privacy Statement inside their Customer Service area, the Frequently Asked Questions, or Help. Most of these statements say that they will only use the information in the aggregate, to spot trends, and they will only send you email about specials if you click a button indicating that you would like to receive these messages (permission email). And most swear they will not pass along the data to another company.

But you may not see these policies, because you have to poke around a bit to find them. Best is when a store puts their promise not to divulge the information on the very form in which they are asking for the data.

We think the situation is improving, particularly in the best stores. But if you have any qualms, look for that privacy statement, and if you don’t find it, or you find it and don’t like it, just exit. There are plenty of stores that really care about privacy, so you don’t have to settle for one that seems indifferent to your concerns.